Nowadays, it is true that in the TIC field related to health care, for example, in the management and transfer of data between hospital information systems, there is a defined standard (named HL7) which has a wide consensus (or the digital radiology case (DICOM)), but in the specific field of health monitoring devices the situation is different.
Although standards for the transmission of biomedical signals are known, they have not been used in a uniform way in the development of monitoring devices. This way, the industry offers monitoring devices whose communication protocol is defined, without any restriction, by the manufacturer.
This tendency and the diversity within the devices are shown not only in the data transmission protocols but also in their operation. The need to unify the transmission and operability criteria has not aroused yet because the signal capturing technology has not been sufficiently developed and consequently it has not been required for the existence of homogeneous devices.
These days, the software developing companies—less related to the sanitary field—and patient assistance device manufacturers follow two developing and marketing lines.
Firstly, the big companies tend to develop integrated suites, in which all the devices that compose them are company property, and the software solutions that they offer are only able to operate on the company devices. The fact that there is no references to devices from a specific manufacturer, for example, in the “Sociedad Española de Medicina” recommendations ([J. M. Soto Ibáñez, N. Perales Rodríguez de Viguri y M. Ruano Marco para la Sociedad Española de Medicina Intensiva, Critica y Unidades Coronarias. ANEXO I: EQUIPAMIENTO DE URGENCIAS. http://www.rcp.semicyuc.org/docs.html]), is partially responsible of that there are different devices from different manufacturers in the intensive medical services and in the coronary units (part of them operating for more than 30 years), said devices being excellent for its operation but incapable to communicate with other devices. This way, if a medical centre would like to implement a technological solution which would allow a local and remote monitoring, it would require a great investment together with a great technological transformation linked to the solution provided by the provider of medical technology.
On the other hand, the software developing companies tend to develop solutions to the patient management and the signal monitoring, although with limitations. Regarding to the monitoring, these systems work with tendencies, that is, an abstract of the vital signals of the patients. In some situations, these solutions are sufficient, although in other situations there is a need of information which said systems are not able to acquire or process. Beside said limitations, the great problem of these systems is the complexity of use of its interface, because of the great number of functions it offers.
There are a lot of systems offering a solution for the computerization of ICUs and patient monitoring scenarios, but said set of functions has been partially developed by two commercial implementations:                eICU Solution (VISICU®). The oldest. It was created as an implementation of telemedicine and it has added some functionalities. Its main limitation is that it interacts with the acquiring systems property of the monitor manufacturers and is limited to transmit them through a network. It does not transmit information from the mechanical ventilators. The usage of the system is wide and its implementation has shown a mortality, stay in the ICU and cost reduction ([Rosenfeld, B. A., T. Dorman, M. J. Breslow, P. Pronovost, M. Jenckes, N. Zhang, G. Anderson, and H. Rubin. 2000. Intensive care unit telemedicine: alternate paradigm for providing continuous intensivist care. Crit. Care Med 28:3925-31]; [Breslow, M. J., B. A. Rosenfeld, M. Doerfler, G. Burke, G. Yates, D. J. Stone, P. Tomaszewicz, R. Hochman, and D. W. Plocher. 2004. Effect of a multiple-site intensive care unit telemedicine program on clinical and economic outcomes: an alternative paradigm for intensivist staffing. Crit. Care Med 32:31-8]).        IMDSoft®. Newer, it has been initiated as a clinical information system and includes some functions of data transmission. The published reports have only evaluated the original application ([Dvir, D., J. Cohen, and P. Singer. 2006. Computerized energy balance and complications in critically ill patients: an observational study. Clin Nutr 25:37-44]).        
In summary, the known systems are dependents of the type and/or manufacturer of the monitoring devices (for example, each monitoring device has a communication protocol defined by its manufacturer and, consequently, it cannot establish a connection with a device or system of another manufacturer, because they do not “understand”). Consequently, a change in a system of a monitoring device (for example, because the device has broken) involves a great investment together with a great technological transformation.